1. Field of the Invention
The present invention relates to a diffraction condition simulation device, a diffraction measurement system, and a crystal analysis system. More particularly, the present invention relates to a novel diffraction condition simulation device, a diffraction measurement system, and a crystal analysis system which are useful for structure analysis and structure evaluation of a crystal sample such as a wafer for a semiconductor or a thin film deposited on the wafer.
2. Description of the Related Art
In crystal structure analysis developed as an analysis of atomic structure, X rays, or particle beams such as neutron beams or electron beams are applied to a crystal sample with an unknown structure, and then, using the diffraction phenomenon of rays scattered by the crystal-sample, the lattice type of the crystal sample or the atomic arrangement in the lattice are clarified. In this crystal structure analysis, for example, X rays are used for the analysis of the electron density of the crystal sample, neutron beams are used for the analysis of the atomic nuclei position of the crystal sample, and electron beams are used for the analysis of the electric potential of the crystal sample.
For such crystal structure analysis, diffraction condition simulation described below is frequently carried out. First, a reciprocal lattice intrinsic to a crystal is calculated on the basis of crystal information such as known lattice constants. Then, using this reciprocal lattice simulation, incident angles and outgoing angles of X ray or particle beams, or ω angles, χ angles, and φ angles as orientation angles of the crystal which satisfy Bragg scattering conditions, or intensity information are obtained.
However, in conventional simulation devices for carrying out such diffraction condition simulation, although a section of the limiting sphere containing reciprocal lattice points which express the Bragg reflection caused by a crystal sample is shown, the displayed section of the limiting sphere cannot be rotated freely and continuously in accordance with a crystal orientation. Thus, it has been impossible to display a desired reciprocal lattice quickly and easily.
Further, in general, there are innumerable diffraction conditions which cause one Bragg reflection, by rotating along a reciprocal lattice vector of a crystal, and the orientation angles, i.e., ω angle, χ angle, φ angle, of the crystal are determined for each of the innumerable diffraction conditions. However, the conventional device is limited to a reflection condition where the x angle of the crystal sample at a minimum, or to the symmetric reflection condition where the incident angle is the same as the outgoing angle, so that the orientation angles of the crystal obtained for one Bragg diffraction condition have been extremely limited.
Moreover, diffraction information obtained from simulation display of a conventional simulation device has been insufficient for the crystal structure analysis. For example, the intensity of the Bragg reflection cannot be obtained, nor can the Bragg reflection be displayed with any distinction between a reflection with the intensity of more than 0 (here, called a general reflection) and a forbidden reflection with the intensity which is theoretically 0, making it difficult to distinguish between the general reflection and the forbidden reflection.
Since the conventional simulation device has a lot of restrictions as to the display of reciprocal lattices or diffraction information as described above, it is earnestly desired to realize a device capable of carrying out improved diffraction condition simulation.